High-pressure spray gun



`uly 30, 1968 w. HEINRICH ET A1. 3,394,890

HIGH-PRESSURE SPRAY GUN Filed Feb. 28, 1966 INVENTORS.' W/LL/ HE//VR/CHKARL SFRA/(EL 3,394,S90 HlGH-PRESSURE SPRAY GUN Willi Heinrich,Rheinkamp-Repelen, and Karl Sprakel,

Mulheim (Ruhr Germany, assignors to Women-Apparatebau, Wolfgang MaasbergL Co., G.m.b.H., Rheinhausen, Germany, a corporation of Germany FiledFeb. 28, 1966, Ser. No. 556,715 Claims priority, application Germany,Nov. 27, 1955, W 40,384 8 Claims. (Cl. 239-526) ABSTRACT F THE DISCLSUREA highpressure spray gun having a mutually controlled auxiliary valveand a main valve of larger flow cross-section which forms a differentialpiston at least partly displaceable under the lluid pressure, the mainvalve member being biased into a valve-closing position by the springagainst which the auxiliary valve member can be shifted by a triggerlever of a piston grip.

Our present invention relates to spray devices for highpressure fluidand, more particularly, to a spray gun for the controlled dispensing ofhigh-pressure liquids.

It has been proposed hitherto to provide spray nozzles in the form ofspray guns having a handle portion provided with a spring-loaded triggeror control lever as part of a piston grip for regulating the rate offlow through a valve means controlled by the lever. The basic elementsof such a device thus include, in addition to the piston grip, a valvebody through which the highpressure fluid passes, a valve membercontrolled by the lever of the grip, and an outlet or nozzle supplied bythe valve means. In general, high-pressure spray guns of this characterrequire the fully mechanical opening and closing of the valve by thecontrol lever such that substantially all of the effort required to openthe valve must be exerted against a spring means tending to close sameand against the pressure of the fluid. In other systems in which thepressure of the fluid is not a factor, the valve member is held againstthe valve seat only by the spring means such that the sealing force,especially when pressures of up to 350 atmospheres are concerned, mustbe sufcient to counteract the tendency of the tluid pressure to unseatthe valve member. Consequently, the spring forces must be relativelyconsiderable and the effort required to operate the valve by atriggering lever is also great. When smaller spring forces are employed,leakage past the valve results. Furthermore, an accurate dispensing ofthe spray and the high rate of flow thereof are not possible sincepractical limits are provided to the crosssection of the valved passagebecause larger cross-sections require still heavier springs whereassmaller cross-sections result in reduction of throughput.

It is the principal object of the present invention, therefore, toprovide a spray gun with trigger-operated valve means which can beemployed without difficulties and without leakage problems at elevatedfluid pressures, and which is yet easily and conveniently operated.

Another object of this invention is to provide an improved spray gun forhigh-pressure fluids which can be accurately controlled so as todispense desired quantities of the fluid and which is characterized by ahigh throughflow capacity.

These objects and others which will become apparent hereinafter areattained, in accordance with the present invention, by a spray gun whichcomprises a main valve means with a relatively large throughilowcross-section and an auxiliary valve means having a relatively smallthroughflow cross-section such that the valve member of the main valvemeans is at least partially displaced by States Patent O vce the forceapplied thereto by the lluid. According to a specific feature of thisinvention, the main valve means includes a reciprocal piston-like mainvalve member exposed to the fluid pressure and normally biased in thedirection of the main-valve seat so as to block the ow of the lluid froma main-valve chamber communicating with the source of such duid; themain valve member forms with an actuating member the auxiliary valvemeans which is operable by a trigger lever of a piston grip. Thus, theauxiliary valve means can include a valve seat formed on the main valvemember which, in turn, is provided with a passage extending from thisauxiliary valve seat to the outlet of the spray gun and is adapted toreceive fluid from an auxiliary valve chamber surrounding the seat uponwithdrawal of the auxiliary valve member by the trigger lever of thepiston grip. In accordance with this feature of the invention, the mainvalve member forms a differential piston exposed to the uid in both ofthese chambers so that a reduction in fluid pressure in the auxiliaryvalve chamber as a consequence of the withdrawal of the auxiliary valvemember from its seat will result in the fluid-pressure displacement ofthe main valve member away from its seat, whereas a blockage of theoutflow from the auxiliary valve member will yield a valve-closingdisplacement of the main valve member and thus a decrease in thethroughow of the main valve means. Thus, the present invention involvesa valve or closure system which is at least partly uidoperated andincorporates a double-valve arrangement in which the movements of a mainvalve are co-ordinated with that of a controlled valve, the main valvebeing disposed between the outlet of the spray gun and the connectingmeans for supplying the high-pressure lluid thereto, while the controlvalve is disposed between the pistol grip and the connecting means.Furthermore, inasmuch as the differential-piston effect of the mainvalve member, when the auxiliary valve is closed, is such that anincrease in the pressure applied in the valve-closing direction of themain valve member increases with in creasing iluid pressure, anypressure increase results in a iirmer sealing of the main valve.Automatic opening of the valve because of iluctuation in the pressure ofthe fluid supply is eliminated. The forces required for operating thevalve at the trigger lever are proportionately small and the hydraulicpressure and force upon this lever are minimum, Still further, therelease of the trigger lever yields a lluid-powered and automatic returnof the main valve member into valve-closing engagement with its seat.

The above and other objects, features and advantages of the presentinvention will become more readily apparent from the followingdescription, reference being made to the accompanying drawing whose soleligure is an axial cross-sectional view through a spray gun embodyingthis invention.

In the drawing, we show a spray gun which comprises a pistol grip lhaving a trigger lever 2 fulcrumed at 2a within a downwardly open recess1a of the pistol-grip barrel 1b. The lever 2 is designed to actuate avalve system generally designated 3 by means of which the flow of fluidto a spray tube 4 is controlled. The tube 4 carries a nozzle 5 which hasan adjustable aperture. A connecting fitting 6 is Welded at 6a to thetubular body 1i of the main valve means 7 in alignment with a radialport 11a. In addition to the main valve means 7, the spray gun isprovided with a co-operating control or auxiliary valve means 8responsive to displacement of the trigger lever 2 for controlling themain valve means '7.

The main valve means 7 comprises, within the tubular body 11, an annularmain valve chamber 9 which is charged with the fluid from the connectingmeans 6 at substantially the full lluid pressure. The chamber 9 thuscommunicates with the radial bore 11a and also with a passage 15a formedin the main valve seat 15, The latter is a ring held against theshoulder 11b of the valve housing 11 by the tube 4 whose male threadedportion 4a is screwed into the correspondingly threaded female portion11C at the left-hand end of the housing 11. Annular seals 16a and 16bare provided respectively between the transverse faces of the maleprojection 4a and the valve seat 15, and between the periphery of thisvalve seat and the inner wall of the valve housing 11. The passage 15ain the valve seat 15 is axially in registry with the passage 4b in thetube 4 and supplies the fluid to the outlet nozzle 5. The main-valvehousing is subdivided by a partition 17 internally into the pressurechamber 9 and an equalizing chamber 10 axially spaced therefrom butaligned therewith.

A main valve member 12 is axially shiftable within the housing 11 andconstitutes a differential piston, as will become apparent hereinafter.The valve piston 12 is of tubular configuration and thus has an axiallyextending bore 13, the piston 12 having a relatively small-diameterportion 12a exposed to fluid pressure within the chamber 9 and a head12b exposed to Huid pressure within the chamber 10. Thus, in the regionof the pressure chamber 9, the cross-section of the main valve member 12is smaller than the cross-section of the member in the region of theequalizing chamber 10, in which the piston-cross-section corresponds tothe cross-section of the equalizing chamber.

The valve body 11 is provided with an axially extending channel 14communicating between a compartment 10a of the equalizing chamber on theright-hand side of the valve piston 12 and the pressure chamber 9. Thecompartment 10a thus forms the auxiliary valve chamber, as will becomeapparent hereinafter. More particularly, the channel 14 opens into acircumferential groove 28 of the forwardly projecting portion 23a of acontrolled valve housing 23, this portion 23a being received within thetubular rearward end 11d of the valve housing 11. The annular groove 28is sealed off from leakage out of the spray gun and from the compartment10a by a pair of O-ring seals 23b axially spaced on opposite sides ofthe groove 28 and seated in respective recesses of the forward portion23a of the control-valve housing 23. From the radial throttle bore 27,communicating with the groove 28, the tluid can pass through an annularclearance between the wall of bore 26 and the controlled-valve member 25slidable therein. The throttle bore ensures that, in an unblockedcondition of aperture 22, the pressure in compartment 10a will be lessthan that in chamber 9. The bore 26 opens into the compartment 10aaround the member 25.

Thus fluid under pressure is supplied to the compartment 10a at theright-hand end of the valve member 12 and its head 12b to urge theforward portion 12a of the valve member into engagement with the seat 15when the pressure within the compartment 10a is equal to that within thechamber 9. The valve is then closed so that iluid cannot flow throughthe passage 4b to the nozzle 5.

The head 12b of the valve member 12 is provided with an annular shoulder12C of substantially identical diameter as that of the equalizingchamber 10 and flanked by a pair of annular double-lift sealing glands19 adapted to be spread apart by the fluid under pressure to ensure aproper sealing engagement between the piston-like valve member 12 andthe inner wall of chamber 10. On the left-hand side of the head 12b ofmember 12, a radial bore 20 is provided between the internal passage 13and the chamber 10. Any fluid within this left-hand portion of chamber10 readily passes through the bore 13 to the nozzle 5 when the valvemember 12 is shifted to the left and the development of a vacuum isprevented by the induction of uid into the left-hand side of chamber 10when the valve member 12 .is displaced to the right.

A sealing engagement between the chambers 9 and 10 is ensured by afurther annular sealing gland 18 of the double-lip which bears upon thesmall-diameter portion 12a of the member 12 and the wall of chamber 9.The glands 1S and 19 are retained in respective grooves of the wall ofchamber 9 and head of 12b of member 12, respectively, so thatundesirable axial movement of member 18 with respect to the housing 11or of seals 19 with respect to the member 12 will be prevented.

The right-hand end of the main valve member 12 is provided with theauxiliary or control valve seat 21 whose aperture 22 has a substantiallysmaller cross-section than that of bore 13 and co-operates withinconically shaped tip ,25a of the axially shftable auxiliary valve member25 to form the auxiliary valve means. The smaller diameter of aperture22 ensures that the effective area of the piston 12, exposed to fluidpressure at compartment 10a and with an efective force to the leftmember greater than the force effective upon the valve member 12 to theright, is a consequence of uid pressure within chamber 9 or evenhuid-pressure vbackup at the left-hand side of the head 12b in chamber10. The forward end 12d of valve member 12 is beveled to cooperatewithin valve seat 15 in a conical fashion, as will be evident from thedrawing.

The control-valve housing 23 is locked within the housing 12 by athreaded cap 31 which is screwed onto the right-hand end portion 11d ofthe housing and clamps the shoulder 23b thereagainst. The control-valvehousing 23 forms a coupling member for the pistol grip 1 and the housing11 and is thus provided at 23e with a threaded male formation lockedinto the forward end of the barrel 1b of the grip. This formation 23Cthreadedly receives a guide bushing 24 within which the valve member 25is shiftable, the bushing 24 forming a seat for a double-lip sealsurrounding the valve member 25.

A guide block 29 is axially shiftable within the recess 1a in the`barrel 1b of the pistol grip 1 and is formed with a slot 32 throughwhich the trigger lever 2 passes. The lever 2 -is provided with acamming protuberance 33 which Ibears upon the rear wall of the slot 32to cam the block 29 to the right when the lever 2 is rotated in thecounterclockwise sense. The block 29 further is `atlixed to theauxiliary valve member 25, which is received within a bore 29a of thisblock, by a setscrew 29b. Furthermore, a spring means 34, advantageouslyformed by dished spring disks of the type generally known as Bellevillewashers, is received within an internally threaded bore 1c in therearward portion of the barrel and bears upon the block 29 to urge it tothe left, ie. into valve-closing direction with respect to the auxiliaryvalve means 28. A guide rod 35 threaded at 35a into the block, 29,passes axially through the area of spring disks 34 and is shiftablewithin a bushing 36 threaded into the bore 1c Aand forming a seat forthe spring means 34. The bushing 36 thus constitutes a pressure screwfor prestressing the spring means 34. To permit adjustment -of thepreload pressure, the right-hand end of screw 36 can extend `from thebarrel 1b and can be provided with a screwdriver slot 36a. A cap 39 canbe threaded onto this free end of the screw to serve as a locking meanspreventing undesired rotation thereof. The nozzle 5, according to aspecific feature of this invention, comprises a threadedreduced-diameter portion 4c of the spray tube 4 onto which. can bescrewed a cap 40 which clamps the annular shoulder of a replaceablecalibrated-bore body 38 against a sealing ring 39. When it is desired tochange the spray aperture, substitute bodies 38 may be clamped in placeby the cap 40.

Operation When hydraulic fluid is supplied via `the connecting tube 6 tothe pressure chamber 9, a corresponding pressure is delivered via thechamber 14, the groove 28, the throttlel bore 27 and the clearance 26surrounding member 25, to the compartment 10a of the equalizing chamber10 to the right-hand side of the head 12b of mem'ber 12. Thus, in astatic condition of the system, the same pressure appears in compartmenta as is supplied to chamber 9 and, since the effective surface area ofthe piston head 12b in terms of the force applied to the piston 12 inthe valve-closing direction (ie. to the left in the drawing) issubstantially larger than the counter-pressure applied in the oppositedirection by the force of fluid upon the exposed area of the narrowportion 12a of this member. Thus, the effective force in thevalve-closing, assuming the absence of back pressure in the tube 4b, isequal to the product of the pressure P and the difference between thenet surface areas A1 and A2 effective in the valve-closing andvalve-opening directions, respectively. The area A1 is, of course,proportional to the difference between the overall diameter a of thepiston head 12b and the diameter of the aperture 22 of valve seat 21.Similarly, the effective area A2 in thel opposite direction isproportional to the difference between the outer dimeter of the member12d and the diameter e of the bore 4b and of the valve seat 15a. Thus,the force holding the piston 12 against its valve seat and blocking theflow of liquid through the bore 4b is proportional to the pressuresupplied in the connecting pipe 6.

Concurrently, a force is applied via the valve member 2S to the springdisk 34. The net force to the right is equal to the product of theeffective area A3 and this pressure P, where the area A3 is proportionalto the difference 'between the diameter y of the bore 22. This force isdimensioned by tightening the screw 36 to be less than the spring forceapplied to the body 29 and thus serves to reduce the effective resistingforce of the spring. When lever 2 is then drawn inwardly(counterclockwise) against the force of spring means 34, the aperture 22is unblocked and the pressure compartment 10a is relieved as the fluidflows therefrom through the bore 13 and the passage 4b. The pressure inchamber 9 remains effective while the pressure in compartment 10a fallssubstantially to zero so that a net force equal to the product of thepressure P and the area A2 is applied to the valve member 12 to shift itto the right, away from the valve seat 15. The fluid supplied via duct 6can then flow past the seat 15 into the passage 4b and thence isdispensed through the nozzle 5. Additional fluid passes via the channel14, t'he annular groove 28, the throttle bore 27 and the guide bore 26into the compartment 10a of equalizing chamber 10. From this chamber theflow of fluid proceeds via the aperture 22 of auxiliary valve seat 21and the bore 13 to the passage 4b and nozzle 5. The throttle bore 27 isso dimensioned that there is la pressure drop between the pressure inthe chambers 9 and 10a during the flow of fluid past the valve seat 15.The effect of this throttle bore is augmented by the Iaspiration offluid through the bore 13 as a consequence of its high rate of flow pastthe conical tip 12d at the narrow gap between the valve member 12 Iandthe seat 15. This ensures that the pressure-resisting reseating of thevalve member will be minimal.

When the lever 2 is released, the spring 34, as a consequence of itsprecompression via adjusting screw 36 and the relieving of the hydrauliccounterpressure applied to member 25, shifts the body 29 to the left andcauses the member 25 to close the aperture 22 and the bore 13. Thepressure within compartment 10a rapidly builds up to equal that withinchamber 9 so that the differential force is again applied Ito member 12to displace it to the left into valve-closing engagement within seat 15.Any fluid compressed in the compartment of chamber 10 at the left-handside of the head 10b escapes via the 'bore 20.

The invention described and illustrated is believed to admit manymodifications within the Iability of persons skilled in the art, allsuch modifications 'being considered within the spirt and scope of theappended claims.

We claim:

1. A high-pressure spray gun for the controlled dispensing ofhigh-pressure fluid, comprising a pistol grip having a flow-controllever; tubular discharge means connected with said pistol grip fordispensing said fluid; main valve means rearwardly of said dischargetube and connectable with a source of said fluid for controlledlysupplying same to said tube, said main valve means having a movable mainvalve member for controlling the flow of fluid through said main valvemeans; auxiliary valve means operable by said lever for fluid biasing ofsaid main valve member to displace same at least partially under thefluid bias as regulated by said auxiliary valve means; housing means forsaid main and auxiliary valve means between said grip and saiddischarging means, said main valve means and said auxiliary valve meansbeing axially aligned between said discharge means and said grip withinsaid housing means, said main valve means comprising a main valve seatcoaxial with said main valve member and engageable thereby upon axialmovement of said main valve member in a valve-closing direction; saidmain valve member being constituted as an axially extending piston, saidmain valve means further comprising a pressure chamber in the region ofsaid main valve seat and a further chamber axially spaced therefrom invalve-opening direction of movement of said main valve member, said mainvalve member having a relatively small effective piston surface exposedto the fluid pressure within said pressure chamber and a relativelylarge effective surface exposed to fluid pressure within said furtherchamber, said housing means being provided with a channelinterconnecting said chambers and with duct means for supplying saidfluid under pressure to said pressure chamber whereby a pressure balancebetween said chamber results in an axial force upon said main valvemember holding same in valve-closing direction against said main valveseat, said valve member being provided with an axially extending boreinterconnecting said chambers, said auxiliary valve means including anauxiliary valve member axially shiftable in said housing means andengaging with said main valve member for selectively blocking theaxially extending bore thereof, said main valve member having arelatively large head Within said further chamber and a relativelysmall-diameter portion extending forwardly from said head toward saidmain valve seat, said auxiliary valve means including an auxiliary valveseat in said head engageable by said auxiliary valve member, saidhousing means being provided with a partition closely surrounding saidsmalldiameter portion and separating said chambers from one another,said main valve member being provided with a port communicating betweenthe portion of said other chamber forwardly of said head and saidaxially extending bore; and sealing means at said partition between saidhousing means and small-diameter portion for preventing the flow offluid past the outer surface of said small-diameter portion between saidchambers.

2. A spray gun as defined in claim 1 wherein said head is provided withsealing means engageable with a wall of said other chamber forpreventing the passage of fluid between portions of said other chamberon opposite sides of said head, said auxiliary valve seat defining avalve aperture of a cross-section less than that of said axiallyextending bore.

3. A spray gun as defined in claim 2 wherein said channel between saidchambers is formed with throttle means for ensuring that the fluidpressure within said other chamber remains below that of said pressurecharnber in `an open condition of said main valve means.

4. A spray gun as defined in claim 3 wherein said auxiliary valve memberis an axially extending rod guided in said housing means and passinginto said grip, said rod having a conical forward portion insertableinto said aperture, said main valve member having a conical forwardportion engageable with said main valve seat, said pistol grip beingprovided with an axially shiftable body engaging said rod, said leverbeing cammingly engageable with said body, said spray gun furthercomprising spring means in said pistol grip acting upon said body forurging said rod into engagement with said auxiliary valve seat, andsealing means between said rod and said housing means rearwardly of saidother chamber for preventing the escape 0f fluid therefrom.

5. A spray gun as defined in claim 4 wherein said housing means isformed with a guide bushing for said rod and with a guide bore receivingsaid rod with annular clearance and opening into said other chamber,said throttle means communicating with said clearance.

6. A spray gun as defined in claim 4 wherein said spring means includesa stack of annular spring disks axially aligned with said valve meansand disposed in said grip rearwardly of said body, said body having arod slidably passing through said disks, said grip being provided withan adjusting screw for axially precompressing said spring means.

7. A spray gun as defined in claim 6, further comprising changeable-borenozzle means on said tube forwardly of said valve means.

8. A spray gun as defined in claim 7 wherein sai nozzle means isthreadedly mounted on said tube, said tube is threadedly secured to saidhousing means, said housing means further 'comprising threaded couplingmeans connecting same with said grip.

References Cited UNITED STATES PATENTS EVERETT W. KIRBY, PrimaryExaminer.

